Method for manufacturing wiring substrate

Abstract

A method for manufacturing a wiring substrate includes preparing two support substrates having one or more product areas, forming a first build-up part including first conductor and insulating layers across the one or more product areas on a first surface of each support substrate, positioning the substrates such that second surfaces of the substrates face each other, and forming a second build-up part including second conductor and insulating layers on each first build-up part. The minimum wiring width and the minimum inter-wiring distance of wirings in the first conductor layers are smaller than those of wirings in the second conductor layers. The forming the first build-up part includes forming a first resist layer having a first resist pattern and forming a conductor pattern according to the first resist pattern for each first conductor layer. The forming the first resist layer includes exposing the first resist layer by direct imaging exposure.

1 . A method for manufacturing a wiring substrate, comprising:
 preparing two support substrates each having at least one product area;   forming a first build-up part comprising a plurality of first conductor layers and a plurality of first insulating layers across the at least one product area on a first surface of each of the support substrates;   positioning the two support substrates such that second surfaces of the support substrates face each other in a thickness direction of each of the support substrates and that the second surface of each of the support substrates is on an opposite side with respect to the first surface of a respective one of the support substrates; and   forming a second build-up part comprising a plurality of second conductor layers and a plurality of second insulating layers on each of the first build-up parts on an opposite side with respect to the respective one of the support substrates such that a minimum wiring width and a minimum inter-wiring distance of wirings in the first conductor layers are smaller than a minimum wiring width and a minimum inter-wiring distance of wirings in the second conductor layers, respectively,   wherein the forming the first build-up part includes forming a first resist layer having a first resist pattern and forming a conductor pattern according to the first resist pattern for each of the first conductor layers, and the forming the first resist layer having the first resist pattern includes exposing the first resist layer by direct imaging exposure.   
     
     
         2 . The method for manufacturing a wiring substrate according to  claim 1 , wherein the positioning the two support substrates to face each other includes bonding the two support substrates to a second support substrate such that the second support substrate is sandwiched between the two support substrates. 
     
     
         3 . The method for manufacturing a wiring substrate according to  claim 2 , further comprising:
 removing the support substrates together with the second support substrate from two structures each comprising the first and second build-up parts after the forming of the second build-up part.   
     
     
         4 . The method for manufacturing a wiring substrate according to  claim 1 , wherein the forming the second build-up part includes forming a second resist layer having a second resist pattern and forming a second conductor pattern according to the second resist pattern for each of the second conductor layers, and the forming of the second resist layer having the second resist pattern includes exposing the second resist layer using a photomask. 
     
     
         5 . The method for manufacturing a wiring substrate according to  claim 1 , wherein the at least one product area in each of the support substrates has a rectangular shape with each side in a range of 80 mm to 240 mm. 
     
     
         6 . The method for manufacturing a wiring substrate according to  claim 1 , wherein the first surface of each of the support substrates has a flatness of ±2.5 μm or less. 
     
     
         7 . The method for manufacturing a wiring substrate according to  claim 6 , wherein each of the support substrates is one of a glass substrate, a silicon substrate, a metal substrate, and a ceramic substrate. 
     
     
         8 . The method for manufacturing a wiring substrate according to  claim 1 , wherein the forming the first build-up part includes forming the first conductor layers each having the conductor pattern such that wirings in the conductor pattern have a minimum width of 2 μm or less and a minimum inter-wiring distance of 2 μm or less. 
     
     
         9 . The method for manufacturing a wiring substrate according to  claim 1 , wherein the first build-up part is formed such that each of the first conductor layers has a thickness of 7 μm or less, and the second build-up part is formed such that each of the second conductor layers has a thickness of 10 μm or more. 
     
     
         10 . The method for manufacturing a wiring substrate according to  claim 1 , wherein the first build-up part is formed such that the first conductor layers include wirings each having an aspect ratio of 2.0 or more and 4.0 or less. 
     
     
         11 . The method for manufacturing a wiring substrate according to  claim 1 , further comprising:
 forming a third build-up part comprising a plurality of third insulating layers and a plurality of third conductor layers on the second build-up part on an opposite side with respect to the first build-up part.   
     
     
         12 . The method for manufacturing a wiring substrate according to  claim 1 , wherein the forming the second build-up part includes forming one of the second insulating layers on the first build-up part on a respective one of the support substrates before positioning the second surfaces of the support substrates to face each other. 
     
     
         13 . The method for manufacturing a wiring substrate according to  claim 1 , wherein the forming the first build-up part includes alternately laminating the first conductor layers and the first insulating layers, and the forming the second build-up part includes alternately laminating the second conductor layers and the second insulating layers. 
     
     
         14 . The method for manufacturing a wiring substrate according to  claim 11 , wherein the forming the third build-up part includes alternately laminating the third conductor layers and the third insulating layers. 
     
     
         15 . The method for manufacturing a wiring substrate according to  claim 2 , wherein the forming the second build-up part includes forming a second resist layer having a second resist pattern and forming a second conductor pattern according to the second resist pattern for each of the second conductor layers, and the forming of the second resist layer having the second resist pattern includes exposing the second resist layer using a photomask. 
     
     
         16 . The method for manufacturing a wiring substrate according to  claim 2 , wherein the at least one product area in each of the support substrates has a rectangular shape with each side in a range of 80 mm to 240 mm. 
     
     
         17 . The method for manufacturing a wiring substrate according to  claim 2 , wherein the first surface of each of the support substrates has a flatness of ±2.5 μm or less. 
     
     
         18 . The method for manufacturing a wiring substrate according to  claim 17 , wherein each of the support substrates is one of a glass substrate, a silicon substrate, a metal substrate, and a ceramic substrate. 
     
     
         19 . The method for manufacturing a wiring substrate according to  claim 2 , wherein the forming the first build-up part includes forming the first conductor layers each having the conductor pattern such that wirings in the conductor pattern have a minimum width of 2 μm or less and a minimum inter-wiring distance of 2 μm or less. 
     
     
         20 . The method for manufacturing a wiring substrate according to  claim 2 , wherein the first build-up part is formed such that each of the first conductor layers has a thickness of 7 μm or less, and the second build-up part is formed such that each of the second conductor layers has a thickness of 10 μm or more.